Fuel feed device

ABSTRACT

In a system in which a housing including a fuel passage is formed by heat welding joining end faces of an upper housing and a lower housing made of a synthetic resin, the melted end portion in the welded portion is pushed out and comes to form a flash. The flash varies in size and shape depending upon the state of melting of the joining end faces and the amount of the portion moved due to the pressing, and the finished housing varies in length. The flash protruding at a portion serving as a fuel passage makes the passage area narrow and increases resistance of the passage, and a weak portion in the flash sometimes drops due to fatigue fracture caused by pulsation of fuel flow. 
     Contact ribs  3   b   , 13   b  facing each other at a portion lower than the joining end faces  3   a   , 13   a  are provided with space grooves  3   c   , 13   c  interposed along the joining end faces  3   a   , 13   a  of the upper housing  3  and the lower housing  13 , and the joining end faces are melted and pressed so that the contact ribs  3   b   , 13   b  of the upper housing  3  and the lower housing  13  may come in contact with each other, thus length of the housing  11  being determined by the contact ribs  3   b   , 13   b . The flash  21  is caused to stay in a staying space  22  closed by the contact ribs  3   b   , 13   b  at the time of completing the heat welding.

FIELD OF THE INVENTION

The present invention relates to a fuel supply system for raising apressure of a fuel and supplying the fuel from a fuel tank to aninternal-combustion engine or the like and, more particularly, to a fuelsupply system that is prevented from influence of flash produced at thetime of forming a housing including fuel passages by welding resinmaterials.

BACKGROUND ART

FIGS. 4 and 5 show a conventional fuel supply system disclosed in theInternational Publication No. WO96/23967. FIG. 4 is a sectional sideview, and FIG. 5 is a plan view. FIG. 6 is an explanatory view of hotplate welding for forming a housing, and FIG. 7 is a sectional viewtaken along the line X-Y-Z.

In the drawings, numeral 1 is a fuel tank, and numeral 2 is an openingof the fuel tank 1. A lid 3 made of a synthetic resin is formed so as tocover the opening 2, and a sealing gasket 4 is interposed between thelid 3 and the fuel tank 1.

A fuel pump 5, a fuel filter 6, a pressure regulator 7, a fuel levelgauge 8, an electric connector 9, and a discharge pipe 10 respectivelyserving as functional parts of a fuel supply system are integrally builtin the lid 3 forming a unit.

The fuel filter 6 is constructed such that a filtration element 12 isaccommodated in a housing 11. Moreover, the lid 3 is a part of thehousing 11, and the fuel filter 6 is suspended from the lid 3. Thehousing 11 is comprised of the lid 3 serving as an upper housing and alower housing 13, and the lower housing 13 is molded of a syntheticresin material. the lid 3 and the lower housing 13 are weldedfluid-tight at a boundary portion 14 over the whole circumference, andthe filtration element 12 is disposed in the internal space.

An intake pipe 15 serving as a fuel intake port is formed at an upperpart on the inner circumferential side of the housing 11 of the fuelfilter 6 and is connected to a discharge pipe of the fuel pump 5.

A pipe 16 (indicated by the one-dot chain line in FIG. 4) forming afirst fuel discharge port, among two fuel discharge ports of the housing11, communicates to the discharge pipe 10 provided on the lid 3 andextends upward from a lower end of the lower housing 13.

A return pipe 18 serving as a second fuel discharge port is formed at alower portion of the lower housing 13 and is connected to the pressureregulator 7.

The electric connector 8 integrally formed with the lid 3 is connectedto a power source and a controller (not shown) outside of the fuel tank1. In the fuel tank 1, the electric connector 8 is connected to the fuelpump 5 through a lead wire not shown, and supplies an electric power toa motor of the fuel pump 5. Further, the electric connector 8 isconnected to the fuel level gauge 8 (shown in FIG. 8) through a leadwire not shown and transmits an electric signal indicating a level ofthe fuel.

The lower housing 13 is made of a conductive synthetic resin anddischarges static electricity generated when the fuel passes through thefiltration element 12 through the electric connector 8.

In the fuel supply system of above construction, when an electric poweris supplied to the fuel pump 5 through the electric connector 8, thefuel pump 5 sucks the fuel through a filter 19, raises a pressure of thefuel, and delivers the fuel to the intake pipe 15 located at the upperpart on the inner circumferential side of the housing 11.

The fuel flows through a passage 20 between the lower housing 13 and thelid 3 in the direction indicated by the arrow A. In the fuel filter 6,the fuel flows downwards in the housing 11, whereby dust or the like inthe fuel is filtered during the passage of the fuel through thefiltration element 12.

The fuel having passed through the filtration element 12, furtherpassing through the discharge pipe 10, is supplied from the pipe 16 toan injector (not shown) of an engine fuel injection system. In thisprocess, the pressure regulator 7 regulates the pressure of the fuelsupplied to the injector so that the pressure may be constant, and asurplus fuel generated due to the change in consumption amount isreturned from the pressure regulator 7 to the fuel tank 1.

In the mentioned construction, the lid 3 and the lower housing 13 arewelded fluid-tight at the boundary portion 14 over the wholecircumference, and hot plate welding is generally employed for thewelding. In the hot plate welding, as shown in FIG. 6, end faces of thelower housing 13 and the lid 3 to be welded are heated to a meltingtemperature with a heating plate 30 as a heating source. Then theheating plate 30 is removed, and the joining end faces of the lowerhousing 13 and the lid 3 are pressed to each other and heat-welded.

In the cross section of the welded portion formed by the hot platewelding, as shown in FIG. 7, an end portion of the molten portion ispushed out due to the pressing and forms a flash 21. The flash 21 variesin size and shape depending upon the state of melting of the joining endfaces and the amount of the portion moved due to the pressing. As aresult, the housing 11 varies in length. The flash 21 protruding at aportion serving as a fuel passage makes the passage area narrow andincreases resistance of the passage. At the same time, pulsation in thefuel flow applies a deformation stress to the flash 21, and a weakportion in the flash 21 sometimes drops due to fatigue fracture. If theflash 21 in a welded portion located upstream from the filtrationelement 12 of the fuel filter drops, the flash 21 is caught by thefiltration element 12. However, if the flash 21 at the welded portiondownstream the filtration element 12 comes to drop, there arise suchproblems as shortage in fuel supply due to clogging of a downstream pipeor engine trouble due to clogging of a nozzle portion of the injectordisposed downstream.

The present invention was made to solve the above-discussed problems andhas an object of providing a fuel supply system in which the housing isrestrained from variation in longitudinal dimensions due to hot platewelding, the flash does not protrude into the passage, and even if anyflash of the welded portion drops, the dropped flash does not flow intothe passage.

DISCLOSURE OF INVENTION

In the fuel supply system according to the invention, for forming apassage for liquid fuel supplied from a fuel pump in a housing, thehousing is formed fluid-tight by heat welding joining end faces of anupper housing and a lower housing both made of a synthetic resin, theupper housing and the lower housing are respectively provided withcontact ribs facing each other at a tier lower down from the joining endfaces, and the joining end faces are subject to melting, pressing andheat welding so that the contact ribs of the upper housing and the lowerhousing may come in contact with each other.

The contact ribs are provided with space grooves interposed along thejoining end faces, the space grooves being formed into a closed stayingspace at the time of completing the heat welding, and flash getting outat the time of heat welding is caused to stay in the staying space.

The staying space formed by the contact ribs is provided at least in apassage downstream a filtration element.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a sectional side view of a fuel supply system showingEmbodiment 1 of the invention.

FIG. 2 is an explanatory view of hot plate welding for forming a housingaccording to the invention.

FIG. 3 is an enlarged partially sectional view of a welded portionaccording to the invention.

FIG. 4 is a sectional side view of a conventional fuel supply system.

FIG. 5 is a plan view of the conventional fuel supply system.

FIG. 6 is an explanatory view of hot plate welding for forming ahousing.

FIG. 7 is a sectional view taken along the line X-Y-Z in FIG. 5.

BEST MODE FOR CARRYING OUT THE INVENTION Embodiment 1

FIG. 1 is a sectional side view of a fuel supply system showingEmbodiment 1 of the invention, FIG. 2 is an explanatory view of hotplate welding for forming a housing according to the invention, and FIG.3 is an enlarged partially sectional view of a welded portion. In thedrawings, numerals 1 to 21 and 30 indicate the same parts as those inthe foregoing description of the conventional system.

The lid 3 and the lower housing 13 are made of a synthetic resinmaterial. Numeral 3 a is a joining end face of the lid 3 forming anupper portion of the housing 11, numeral 3 b is a contact rib providedalong the joining end face 3 a at a portion a little lower than thejoining end face 3 a, and numeral 3 c is a space groove provided betweenthe joining end face 3 a and the contact rib 3 b. Numeral 13 a is ajoining end face of the lower housing 13, and this joining end face 13 aof the lower housing 13 and the joining end face 3 a of the lid 3 arewelded and formed into the boundary portion 14. End faces of a partitionwall of the housing 11 perpendicular to the boundary portion 14 are thejoining end faces 3 a, 13 a, and an outer shell of the housing 11 and apassage are formed fluid-tight by welding and joining the lid 3 and thelower housing 13 at the joining end faces 3 a, 13 a.

Numeral 13 b is a contact rib provided along the joining end face 13 aat a portion a little lower than the joining end face 13 a, and numeral13 c is a space groove provided between the joining end face 13 a andthe contact rib 13 b. The joining end faces 3 a, 13 a and the contactribs 3 b, 13 b of the lid 3 and the lower housing 13 are facing eachother respectively.

In the hot plate welding of the lid 3 and the lower housing 13, as shownin FIG. 2, the heating plate 30 serving as the heating source isinterposed between the joining end face 3 a of the lid 3 and the joiningend face 13 a of the lower housing 13, and both of the joining end facesare heated to a melting temperature. Then the heating plate 30 isremoved, and the joining end faces are pressed and welded fluid-tighttogether. In this process, since the contact ribs 3 b, 13 b of the lid 3and the lower housing 13 are at a portion a little lower than thejoining end faces 3 a, 13 a and are not heated up to a melting andsoftening temperature, the contact ribs 3 b, 13 b are not deformed bythe pressing.

Accordingly, deformation of the boundary portion 14 stops at a portionwhere the contact ribs 3 b, 13 b come in contact with each other, andthe finished housing 11 has a constant length.

Further, as shown in FIG. 3, when the lid 3 and the lower housing 13 arewelded, a staying space 22 is formed by the space grooves 3 c, 13 c ofthe lid 3 and the lower housing 13. In this process, the flash 21, thatis formed by pressing and deforming the joining end faces of the lid 3and the lower housing 13, can be caused to remain in the staying space22. As a result, forming the staying space 22 on the side where the fuelflows makes it possible to prevent the passage area from narrowing dueto protruding of the flash 21 and restrain the flash 21 from droppingdue to pulsation of the flowing liquid fuel. Even if the flash 21 drops,it is possible to prevent the downstream pipe from clogging by causingthe flash 21 to remain in the staying space 22 so as not to flowdownstream.

It may be the most preferable to provide the space grooves 3 c, 13 c andthe contact ribs 3 b, 13 b on the circumference of the joining endfaces. In this case, however, the sectional area of the fuel supplysystem becomes large, which is not desirable from the viewpoint of downsizing of the system. Therefore, it is also preferable that a portionnot seriously affected by the flash 21 is dotted with the contact ribs 3b, 13 b within a limited range in which the dimensions after the heatwelding are constant. It is also preferable that the staying space 22 isformed only at a portion where dropping of the flash 21 influences thefuel system and the other parts remains in the same welding structure asin the prior art. The liquid fuel is supplied by driving the fuel pump 5in the same manner as in the conventional system, and therefore furtherdescription thereof is omitted herein.

Industrial Applicability

As has been described above, in the present invention, the contact ribs3 b, 13 b are provided with the space grooves 3 c, 13 c interposed alongthe joining end face 3 a of the lid 3 and the joining end face 13 a ofthe lower housing 13 at a portion lower than the joining end faces 3 a,13 a. As a result, when both of the joining end faces are heated,pressed and welded to each other, deformation of the joining end facesis stopped at the position where the contact ribs 3 b, 13 b come incontact with each other, and dimensions of the finished housing 11becomes constant.

The space 22 formed on the passage side at the time of completing thewelding causes to stay therein the flash 21 produced by the pressing anddeformation process, thereby preventing the passage area from beingnarrowed, restraining the flash 21 from dropping due to the pulsation ofthe flowing liquid fuel, the flash 21 once dropped stays in the space22, and the downstream pipe is prevented from clogging.

What is claimed is:
 1. A fuel supply system comprising: a housingcontaining a fuel pump and a passage for liquid fuel supplied from thefuel pump, wherein: said housing is formed fluid-tight by joined endfaces of an upper housing and a lower housing, both made of a syntheticresin; said upper housing and said lower housing are respectivelyprovided with contact ribs facing each other at positions laterallyadjacent to the joining end faces; and said joined end faces have beenheat welded together, and both contact ribs are in contact with eachother.
 2. The fuel supply system according to claim 1, wherein spacegrooves are interposed between the contact ribs and the joined endfaces, the space grooves being formed into a staying space closed withsaid ribs at the time of completing the heat welding, so that any flashfrom the heat welding remains in the staying space.
 3. The fuel supplysystem according to claim 2, wherein the staying space formed by thecontact ribs is provided at least in a passage downstream of afiltration element.
 4. The fuel supply system according to claim 1,wherein the joined end faces and the contact ribs are laterallyseparated by a space groove.
 5. The fuel supply system according toclaim 1, wherein the joined end faces and the contact ribs are botharranged on an outer wall of the housing.
 6. The fuel supply systemaccording to claim 5, wherein the joined end faces and the contact ribsare laterally separated by a space groove.
 7. The fuel supply systemaccording to claim 5, wherein the joined end faces are joined on anouter side of the outer wall, and the contact ribs are in contact on aninner side of the outer wall.
 8. The fuel supply system according toclaim 1, wherein the joined end faces and the contact ribs are botharranged on a wall of the passage for liquid fuel supplied from the fuelpump.
 9. The fuel supply system according to claim 8, wherein the joinedend faces and the contact ribs are laterally separated by a spacegroove.
 10. The fuel supply system according to claim 8, wherein thejoined end faces are joined on an outer side of the wall of the passage,and the contact ribs are in contact on an inner side of the wall of thepassage.
 11. A fuel supply system in which a passage for a liquid fuelsupplied from a fuel pump is formed in a housing, said passage beingsunk into a fuel tank integrally with a fuel pump and the housing,wherein: said housing is formed fluid-tight by heat welding joining endfaces of an upper housing and a lower housing both made of a syntheticresin; said upper housing and lower housing are respectively providedwith contact ribs facing each other at a portion lower than the joiningend faces; and said joining end faces are subject to melting, pressingand heat welding so that both contact ribs may come in contact with eachother; and said contact ribs are provided with space grooves interposedalong the joining end faces, the space grooves being formed into a spaceclosed with said ribs at the time of completing the heat welding, and aflash formed at the time of heat welding is caused to stay in saidspace.
 12. The fuel supply system according to claim 11, wherein thespace formed by the contact ribs is provided at least in a passagedownstream of a filtration element.